N5296s,
That is exactly the sort of failure mode I am talking about. An excellent example of a seemingly innocuous fault that later manifests itself as somthing far more sinister!
The worst fault I had to deal with inflight was a rough running engine at night. I had been to Flagler county airport along with 2 other pilots, each of us in a c150. We landed after a short flight from ormond beach, and stopped for tea at hijackers cafe ( I can highly reccomend the chicken kabobs!
).. After which, we decided to fly up the coast to St Augustine, about a 25 min flight.
During the Pre-take off power check, I got rough running on the right mag, so following the training I had, I did a slightly lean power run to clear the fouled plug, which worked a treat, and restored full power & smooth running.
We took off, and about 5 mins into the leg, my engine started running rough again, which for a newly qualified ppl at night, is quite worrying! Switching to the left only mag cured it, but I immediatly diverted back to Ormond beach, and landed without incident.
In the morning, I spoke to the mechanic, who said it was simply a worn plug, but to me it made sense to return to base rarther than press on over dark, unfamiliar terrain with no real need to continue the flight, which was simply hour building...